Is internal thoracic artery resistant to reperfusion injury? Evaluation of the storage of free internal thoracic artery grafts

Objectives: The in situ internal thoracic artery (ITA) is recognized as the best conduit for coronary artery bypass surgery. The ITA-if it is used as an in situ graft-has a much higher late patency rate than any other arterial graft, including a free ITA graft. We sought to determine if the use of the ITA as an in situ/free graft and its storage in preservation solutions, have an effect on endothelial function. Methods: The ITA was harvested as either a free or in situ graft in a porcine model. Free grafts were stored in different preservation solutions (saline, Custodiol and Tiprotec [both Kohler Chemie GmbH, Bensheim, Germany]). The ITA was anastomosed off pump to the left anterior descending artery (as in situ/free graft). Freshly harvested ITA served as a control. After 2 hours of reperfusion, the implanted grafts were harvested. The assessment of endothelial function, histopathological analysis, and gene expression were performed. Results: Endothelial function and integrity were severely impaired after reperfusion in the free ITA groups, however, it was partially preserved in the Tiprotec group. Reperfusion injury resulted in increased nitro-oxidative stress, DNA breakage, vascular cell adhesion protein 1, intercellular adhesion molecule-1, and caspase-3 scores, and a decreased endothelial nitric oxide synthase score in the free ITA groups. The in situ ITA graft showed no signs of injury. mRNA levels were significantly altered among the groups. Conclusions: An early, severe endothelial dysfunction of the stored, free ITA as described, could be completely prevented by the use of an in situ ITA graft. Tiprotec might be a feasible option for storage of free arterial grafts during coronary artery bypass grafting.